Flushing valve for inboard boat engines

A flushing valve for an inboard boat engine that is installed in a conduit normally used for conducting ambient water to the engine for cooling it, and that can selectively supply flushing liquid to the engine from a pressurized source or from an unpressurized source, said flushing valve comprising in combination:

• a hollow body including a first port, a second port, and a third port;
• said hollow body containing a first biased check valve preventing outward flow through said first port and preventing inward flow through said first port until the outside pressure exceeds the inside pressure by P.sub.1, and permitting inward flow in relation to the difference between the outside pressure and the inside pressure when the outside pressure exceeds the inside pressure by at least P.sub.1, whereby the flow of ambient water to the engine is modulated in relation to the engine speed to avoid overcooling the engine at low speeds;
• said hollow body containing a second biased check valve preventing outward flow through said second port and preventing inward flow through said second port until the outside pressure exceeds the inside pressure by P.sub.2 where P.sub.2 is greater than P.sub.1 ;
• first means for connecting said first port to the conduit for receiving the ambient water;
• second means for removably connecting said second port to a supply of a flushing fluid;
• third means for connecting said third port to the conduit for discharging liquid from said third port to the engine;
• and,
• spoiler means operatively associated with said second biased check valve for selectively holding open said biased check valve.